process for at least partial reduction of hematite to magnetite

摘要

Haematite is partially or wholly reduced to magnetite using a fluidized bed process which employs a liquid hydrocarbon fuel injected into a fluidized bed of the haematite at a temperature in general above 600 DEG C. in an atmosphere containing only 40-60% of the oxygen required for complete combustion of the fuel. The reaction vessel may contain one or more fluidized beds which are heated in turn by the gases of the combustion taking place within the fluidized beds. There may be preheating, combustion and reducing zones, and where there are two reduction stages complete reduction to magnetite may take place at temperatures as low as 525 DEG C. The waste gases may be recycled to the last of the beds in which combustion of fuel and reduction of ores takes place. Extra fuel, oxygen, steam and inert gases may be introduced at any of the fluidized beds. The ores employed may be comminuted before or after the process and separation by electromagnet is effected after the process.